Ensure the NAS network configuration does contain only DNS servers able to resolve your internal domain. With a single server, or a single ADDC, this would be the LAN IP address of your WIN2012R2 server on the intranet subdomain - which is also your ADDC domain.

If there other (or more) DNS servers configured, neither the domain intranet.cshcc.org.hk nor the ADDC server WIN2012R2.intranet.cshcc.org.hk IP addresses can be resolved. This does lead to the failure.

An nslookup or dig for intranet.cshcc.org.hk and WIN2012R2.intranet.cshcc.org.hk must return the LAN IP address of your ADDC, which is your Windows Server, at least.

Dear Kurt,Thanks very much for your reply.There is only one ADDC within the network. I try to SSH in and use nslookup to check if the NAS can resolve the server name and internal domain name returns the correct IP address to me.I am wondering would it be something blocked the communication between the NAS and the DNS when try to do authenicaton ?Henry

schumaku wrote:Hi Henry,

Ensure the NAS network configuration does contain only DNS servers able to resolve your internal domain. With a single server, or a single ADDC, this would be the LAN IP address of your WIN2012R2 server on the intranet subdomain - which is also your ADDC domain.

If there other (or more) DNS servers configured, neither the domain intranet.cshcc.org.hk nor the ADDC server WIN2012R2.intranet.cshcc.org.hk IP addresses can be resolved. This does lead to the failure.

An nslookup or dig for intranet.cshcc.org.hk and WIN2012R2.intranet.cshcc.org.hk must return the LAN IP address of your ADDC, which is your Windows Server, at least.

I have this exact problem with QNAP TS-831XU. have set the DNS to the DC's NICs (both Primary and secondary), the time is the same but cant join the domain.Note: The nas has ever been on this domain before but my college disjoined it when I was on leave. Now I cant get it back to the same domain.